Insulator for a set of electrical distribution bars



July 10, 1962 P. M. AMADON 3,043,904

INSULATOR FOR A SET OF ELECTRICAL DISTRIBUTION BARS Filed June 22, 1960 l2 2 IO 2 PAUL MARI US AMADON BY K FF-Tlm A'ITORNEY INVENTOR INSULATOR FOR A SET OF ELECTRICAL DISTRIBUTION BARS Paul Marius Amadon, Vesinet, Seine et Olse, France, as-

signor to La Telemecanique Electrique, Nanterre, France, a joint-stock company of France Filed June 22, 1960, Ser. No. 37,926 Claims priority, application France July 3, 1959 6 Claims. (Cl. 174-158) The present invention concerns an insulating device adapted to support a set of electrical distribution bars, this set of bars being preferably placed in a metal duct, a bar box or the like.

The technical operating conditions for such bar boxes require that certain'precautionsbe taken in the construction of the insulators.

Allowance is generally made for a certain rise of the latent temperature of the .set of bars and, consequently, the material of the insulators has to be refractory, generally ceramic.

On the other hand in distribution systems very violent accidental short-circuits can happen. The sets of bars are then subjected to very highelectro-dynamic forces, and, in the case of sheathed bars, the arcs initiated at any point start travelling along the set of bars and jump over the insulating supports; accordingly these supports must be of a refractory material and be sufficiently resistant to lateral forces. The various impacts and vibrations likely to crack them must also be reckoned with.

The prior art generally provides ceramic insulators forming a compact block providing saddle top shaped seatings in the direction of the bars which are inserted therein.

However, it has not been possible to prevent the insulators from breaking at locations which are, moreover, diificult of access; the crack formed can be in any direction whatever, for instance oblique with respect to the bars. Dust accumulates in such cracks, and insulation between two adjacent bars disappears completely. Attempts have been made to overcome this drawback by placing, between the support and the metal sheath, a felt sole-plate partially surrounding the support, but this precaution has been found to be insufficient.

In another type of embodiment, the ceramic support has been cut into as many elements as there are gaps between the bars, plus two extreme end elements, a joint between each insulating element being made in the axis of the supported bars. Thus, in the event of strong forces, the insulating elements can spread slightly apart without the formation of transverse cracks. But this solution requires a separate assembly within the sheath of each elemental support, which considerably increases the time and cost of assembly.

Ceramic supports, also formed of separate elements but imprisoning the distribution bars therebetween, are likewise known, with the assembly being held together by lateral resilient means.

The present invention provides insulators of the saddleseating type, adapted to support a set of staggered electri cal distribution bars in a metal sheath, overcoming the aforesaid drawbacks.

According to the invention, each insulator is bedded in a resilient casing and is provided with at least one fracture guide formed in each seating and in the direction of the length thereof, whereby, in the event of violent lateral force, a directed fracture takes place and the resilient casing firmly retains the twoportions of the insulator resulting from the fracture in order to preserve the original efliciency of the insulator without the need for replacement.

Other features and advantages of the present inven- United States Patent 3,043,904 Patented July 10, 1962 tion will become apparent from the ensuing description given with regard to the accompanying drawing, in which:

FIGURE 1 is a plan view of an insulator designed in accordance with the invention, bedded in its resilient sole;

FIGURE 2 is a side elevation of this unit, partially broken away, inserted into a sheath;

FIGURE 3 is an elevation of one inter-saddle web element after fracture; and,

FIGURE 4 is a plan view showing a positioning device for the insulator and its sheath, which latter is shown in part.

In the embodiment illustrated, the insulator in accordance with the invention comprises a cast ceramic support 1 having saddle-seatings 2 adapted to receive the distribution bars. One such bar is shown at 3 in FIGURE 2.

The support 1 is bedded into'a resilient casing 4 forming a sole-plate comprising channels 5 closed at their ends by tabs 6, as well as end flaps 7. The channels 5 grip two longitudinal flange portions 8 of the insulator and the flaps 7 bear against two parallelepipedic projections 9 of the support 1.

The upright portions of the support or inter-saddle webs 10, defining the saddle-seatings 2, have thereon a peripheral bead 11 adapted to' increase the leakage path between two adjacent bars.

The seats of the saddle-seatings 2 are dressed longitudinally to provide a fracture guide 12. A similar fracture guide 12a is also dressed, in line with the guide 12, into the face of support 1 opposite the saddled side.

The support 1, embedded in its resilient casing 4, is simply laid into a metallic sheath 13 (FIGURES 2 and 4) and the two parallelepipedic projections 9 are inserted into U-shaped members 14 secured inside the sheath.

A supporting hook 15 for the lateral earthing bar 16 can be inserted into a notch 17 formed in one of the projections 9 of the support, to be located between said projection and the corresponding flap 7 of the casing 4.

It will be appreciated that when the bars are subjected to high electrodynamic forces, the insulator breaks at the location of at least one fracture guide 12 and its complementary guide 12a, which produces a fracture 18 (FIG- URE 3) between at least two distinct portions of the insulator which remain firmly in place due to the resilient casing 4. Since the insulator is only broken in the longitudinal axis of the bar which it supports, it retains its ability to fulfill its intended function without having to be replaced.

It will be understood that the above description has been given merely by way of explanation, without any intention of limitation and that the invention is adaptable to numerous embodiments without exceeding its scope.

I claim:

1. A refractory insulator, resistant to lateral forces, of a compact saddle-top design, having end members and a sole-plate adapted to support a set of electrical distribution bars in a metal sheath along with other similar insulators staggered alternately upright and inverted along the length of the set of bars, comprising a refractory support, saddle-shaped seatings in this support adapted to receive the distribution bars, at least one fracture guide formed at the bottom of each saddle-seating and in the direction of the length thereof, and a resilient casing having said support bedded therein, whereby in the event of violent lateral forces, directed fractures take place and the casing firmly retains the parts of the support resulting from the fracture.

2. A refractory insulator, resistant to lateral forces, of a compact saddle-top design, having end members and a sole-plate adapted to support a set of electrical distribution bars in 'a metal sheath along with other similar insulators staggered alternately upright and inverted along thelength of the set of bars, comprising a refractory aesaeoa support, saddle-shaped seatings in this support adapted to receive the distribution bars, a fracture guide formed in the bottom of each saddle-seating and in the direction of the length thereof, a second fracture guide formed in line with the first guide and on the support face opposite to the saddle-seating, and a resilient casing having said support bedded therein, whereby in the event of violent lateral force directed fractures take place and the casing firmly retains the parts of the support resulting from the fracture.

3. A refractory insulator, resistant to lateral forces, of a compact saddle-top design, having end members and a sole-plate adapted to support a set of electrical distribution bars in a metal sheath along with other similar insulators staggered alternately upright and inverted along the length of the set of bars, comprising a refractory support, saddle-shaped seatings in this support adapted to receive the distribution bars, at least one fracture guide formed at the bottom of each saddle-seating and in the direction of the length thereof, two longitudinal flanges on the support, a resilient casing having said support bedded therein, and channels in this casing, closed at their ends, gripping said two longitudinal flanges of the support, whereby in the event of violent lateral forces, directed fractures take place and the casing firmly retains the parts of the support resulting from the fracture.

4. Arefractory insulator, resistant to lateral forces, of

a compact saddle-top design, having end members and a sole-plate adapted to support a set of electrical distribution bars in a metal sheath along with other similar insulators staggered alternately upright and inverted along the length of the set of bars, comprising a refractory support, saddle-shaped seatings in this support adapted to receive the distribution bars, at least one fracture guide formed at the bottom of each saddle-seating and in the direction of the length thereof, two longitudinal flanges on the support, two projecting parallelepipedic end members, a resilient casing having said support bedded therein, channels in this casing, closed at their ends, gripping said two longitudinal flanges of the support, end flaps of this casing bearing against said projecting parallelepipedic end members of the support, whereby in the event of violent lateral forces, directed fractures take place and the casing firmly retains the parts of the support resulting from the fracture.

5. A refractory insulator, resistant to lateral forces, of a compact saddle-top design, having end members and a sole-plate adapted to support a set of electrical distribution bars in a metal sheath along with other similar insulators staggered alternately upright and inverted along the length of the set of bars, comprising a refractory support, saddle-shaped seatings in this support adapted to receive the distribution bars, at least one fracture guide formed at the bottom of each saddle-seating and in the direction of the length thereof, two longitudinal flanges on the support, two projecting parallelepipedic end members, a resilient casing having said support bedded therein, channels in this casing, closed at their ends, gripping said two longitudinal flanges of the support, end flaps of this casing bearing against said projecting parallelepipedic end members of the support, U-shaped pieces secured inside the sheath and receiving said projecting parallelepipedic end members of the support, which support is simply laid in the metal sheath, whereby in the event of violent lateral forces, directed fractures take place and the casing firmly retains the parts of the support resulting from the fracture.

6. A refractory insulator, resistant to lateral forces, of a compact saddle-top design, having end members and a sole-plate adapted to support a set of electrical distribution bars in a metal sheath along with other similar insulators staggered alternately upright and inverted along the length of the set of bars, comprising a refractory support, saddle-shaped seatings in this support adapted to receive the distribution bars, at least one fracture guide formed at the bottom of each saddle-seating and in the direction of the length thereof, two longitudinal flanges on the. support, two projecting parallelepipedic end members, a resilient casing having said support bedded therein, channels in this casing, closed at their ends, gripping said two longitudinal flanges of the support, end flaps of this casing bearing against said projecting parallelepipedic end members of the support, U-shaped pieces secured inside the sheath and receiving said projecting parallelepipedic end members of the support, which support is simply laid in the metal sheath, a lateral earthing bar, a notch formed in one of the projecting parallelepipedic end members of the support, a supporting hook for said lateral bar inserted in said notch, whereby in the event of violent lateral forces, directed fractures take place and the casing firmly retains the parts of the support resulting from the fracture.

References Cited in the file of this patent UNITED STATES PATENTS 2,059,988 Frank Nov. 3, 1936 2,310,919 Adam Feb. 16, 1943 2,749,385 Adam June 5, 1956 2,881,242 Kron Apr. 7, 1959 

